Treatment of potable water

ABSTRACT

Methods and systems for treating water for potable use or consumption are described. In an embodiment, a method for treating water for potable may include adding an effective amount of a magnesium compound to supply water to be treated. The method may also include adding an effective amount of a flocculation aiding metal salt to the supply water. The method may further include removing one or more contaminants from the supply water to provide treated water. Other methods and systems are described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 61/978,328, entitled “Treatment of Potable Water”filed on Apr. 11, 2014; this application also claims the benefit of U.S.provisional patent application Ser. No. 61/898,150, entitled “Treatmentof Potable Water” filed on Oct. 31, 2013, the entirety of both of whichapplications is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to potable water treatment, andmore particularly relates to the use of magnesium compounds in thetreatment of potable water.

BACKGROUND

Potable water treatment systems may typically be designed to take a rawwater supply, whether from surface sources, such as rivers, lakes,reservoirs, or from groundwater sources, such as wells and aquifers, andprocess the raw water for distribution and consumption. The processingmay involve removing constituents from the water that may be harmful,and may also include removing other constituents that may impartundesirable color, taste, turbidity or odor. The removed constituentsmay be in the form of dissolved solids or gases, suspended solids orgases, miscible or immiscible liquids, and may be organic and/orinorganic in nature. These constituents are often measured as TotalOrganic Carbon (“TOC”), Total Dissolved Solids (“TDS”), Total SuspendedSolids (“TSS”), and Turbidity (“NTU”). In some situations, specificconstituents such as minerals may be identified in more detail.

SUMMARY

In an implementation, a method may include adding an effective amount ofa magnesium compound to supply water to be treated. The method may alsoinclude adding an effective amount of a flocculation aiding metal saltto the supply water. The method may further include removing one or morecontaminants from the supply water to provide treated water.

One or more of the following features may be included. The magnesiumcompound includes one or more of magnesium hydroxide and magnesiumoxide. The magnesium hydroxide may exhibit an alkaline magnesiumhydroxide purity of between about 85% to about 100%. The magnesiumhydroxide may exhibit a caustic magnesia activity of between about 50seconds to about 1440 minutes. The magnesium hydroxide may exhibit aparticle size of between about 0.1 micron to about 50 microns. Themagnesium hydroxide may exhibit a specific surface area of between about9 m²/g to about 200 m²/g. The magnesium hydroxide may exhibit astabilized residuals test value of between about 1 milligram to about 50grams. The magnesium oxide may exhibit an alkaline magnesium oxidepurity of between about 85% to about 100%. The magnesium oxide mayexhibit a caustic magnesia activity of between about 50 seconds to about1000 seconds. The magnesium oxide may exhibit a particle size of betweenabout 0.1 micron to about 30 microns. The magnesium oxide may exhibit aspecific surface area of between about 9 m²/g to about 300 m²/g.

The flocculation aiding metal salt may include one or more of alum,ferrous sulfate, ferric sulfate, ferrous chloride, and ferric chloride.Adding the effective amount of the magnesium compound may include addingthe magnesium compound to the supply water prior to adding theflocculation aiding metal salt. Adding the effective amount of themagnesium compound may include adding the magnesium compound generallyalong with adding the flocculation aiding metal salt.

Adding the effective amount of the magnesium compound includes measuringa quality of the treated water. The method may further include adjustingthe effective amount of the magnesium compound based upon, at least inpart, the measured quality of the treated water. The quality of thetreated water may include one or more of an alkalinity of the treatedwater and a pH of the treated water. The quality of the treated watermay include a corrosivity of the treated water as indicated by aLangelier Index of the treated water. The method may further includedetermining an anticipated alkalinity depletion associated with addingthe flocculation aiding metal salt. The effective amount of themagnesium compound may be based upon, at least in part, amountoffsetting at least a portion of the anticipated alkalinity depletion.

The method may further include adding an effective amount of a polymercontaminant removal aid including one or more ofpolyepichlorohydrin-dimethylamine, polyamine,polydiallyl-dimethylammonium chloride (polyDADMAC), polyacrylate,polyamide, a Mannich polymer, and polyacrylamide. Adding the magnesiumcompound may include adding an admixture of the magnesium compound and aalkaline earth metal compound. Removing one or more contaminants fromthe supply water may include one or more of flocculation, coagulation,sedimentation, and filtration. Removing one or more contaminants fromthe supply water may include filtration. The method may further includerecycling a residual magnesium compound from a filter element andrecycling the residual magnesium compound into the supply water.

According to another implementation, a method may include treatingsupply water. Treating the supply water may include adding an effectiveamount of a flocculation aiding metal salt to the supply water andremoving one or more contaminants from the supply water. Treating thesupply water may provide treated potable water. The method may alsoinclude determining a corrosivity associated with the treated potablewater. The method may further include adding an effective amount of amagnesium compound to the supply water based upon, at least in part, thedetermined corrosivity associated with the treated potable water toachieve a desired reduced corrosivity associated with the treatedpotable water.

One or more of the following features may be included. Determining thecorrosivity associated with the treated potable water may includedetermining a Langelier's Index associated with the treated potablewater. Adding the effective amount of the magnesium compound may includeadding the magnesium compound to the supply water prior to adding theflocculation aiding metal salt. Adding the effective amount of themagnesium compound may include adding the magnesium compound generallyalong with adding the flocculation aiding metal salt.

The magnesium compound may include magnesium hydroxide exhibiting analkaline magnesium hydroxide purity of between about 85% to about 100%.The magnesium hydroxide may exhibit a caustic magnesia activity ofbetween about 50 seconds to about 1440 minutes. The magnesium hydroxidemay exhibit a particle size of between about 0.1 micron to about 50microns. The magnesium hydroxide may exhibit a specific surface area ofbetween about 9 m²/g to about 200 m²/g. The magnesium hydroxide mayexhibit a stabilized residuals test value of between about 1 milligramto about 50 grams. The magnesium compound may include magnesium oxideexhibiting an alkaline magnesium oxide purity of between about 85% toabout 100%. The magnesium oxide may exhibit a caustic magnesia activityof between about 50 seconds to about 1000 seconds. The magnesium oxidemay exhibit a particle size of between about 0.1 micron to about 30microns. The magnesium oxide may exhibit a specific surface area ofbetween about 9 m²/g to about 300 m²/g.

According to yet another implementation, a method may include adding aneffective amount of a flocculation aiding metal salt to supply water.The method may also include removing one or more contaminants from thesupply water using a bio-filtration process. The method may furtherinclude adding an effective amount of a magnesium compound to the supplywater to improve performance of the bio-filtration process.

One or more of the following features may be included. The magnesiumcompound may include magnesium hydroxide exhibiting an alkalinemagnesium hydroxide purity of between about 85% to about 100%. Themagnesium hydroxide may exhibit a caustic magnesia activity of betweenabout 50 seconds to about 1440 minutes. The magnesium hydroxide mayexhibit a particle size of between about 0.1 micron to about 50 microns.The magnesium hydroxide may exhibit a specific surface area of betweenabout 9 m²/g to about 200 m²/g. The magnesium hydroxide may exhibit astabilized residuals test value of between about 1 milligram to about 50grams. The magnesium compound may include magnesium oxide exhibiting analkaline magnesium oxide purity of between about 85% to about 100%. Themagnesium oxide may exhibit a caustic magnesia activity of between about50 seconds to about 1000 seconds. The magnesium oxide may exhibit aparticle size of between about 0.1 micron to about 30 microns. Themagnesium oxide may exhibit a specific surface area of between about 9m²/g to about 300 m²/g.

Adding the effective amount of the magnesium compound may include addingthe magnesium compound to the supply water prior to adding theflocculation aiding metal salt. Adding the effective amount of themagnesium compound may include adding the magnesium compound generallyalong with adding the flocculation aiding metal salt.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will become apparent from the description, the drawings, andthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts an example water treatment system, whereinthe identified coagulant may include the use of metal salts or apolymer.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Supply water may typically be treated in a variety of manners to make itsuitable for potable use. For example, water that may ultimately beintended for potable use may often be supplied from surface sources suchas rivers, lakes, reservoirs, etc., or from ground water sources, suchas wells, aquifers, and the like. The water supply may typically includevarious contaminants that may make the supply water unsuitable, orundesirable for potable use. Consistent with embodiments of the presentdisclosure, supply water may be processed to provide treated water thatmay be suitable for potable use. In an embodiment, treatment of supplywater may generally include adding a magnesium compound to the supplywater and adding a flocculation aiding metal salt to the supply water.One or more contaminants may be removed from the supply water to providetreated water that may, in some embodiments, be suitable for potableuse.

Consistent with some embodiments, magnesium compounds, such as magnesiumhydroxide and/or magnesium oxide, may be utilized in combination withflocculation aiding metal salts to improve the efficiency of treatmentof water for potable use (e.g., which may also be referred to as“treating potable water,” or similar phrasing). For example,flocculation aiding metal salts that may be utilized in connection withthe treatment of potable water may include, but are not limited to,alum, ferrous sulfate, ferric sulfate, ferrous chloride, and ferricchloride. Such metal salts may serve as flocculation aids to facilitatethe removal of contaminants from supply water. In some situations, theflocculation aiding metal salts may deplete the alkalinity of the supplywater, which may lead to treated water having an alkalinity, and/or pH,below a desired level. In some embodiments, the magnesium compounds may,at least in part, offset the alkalinity reduction caused by theflocculation aiding metal salts. In some such embodiments, the treatedwater may have an alkalinity within a desired alkalinity range. Further,in some such embodiments, the treated water may have a pH that may bewithin a desired pH range for the treated water. In some embodiments,the magnesium compounds may provide treated water having an alkalinityand/or a pH within a desired range, which may reduce and/or eliminatethe need for alkalinity and/or pH modifying processes and/or substances,such as caustic soda and/or lime, which may be expensive and/orpotentially dangerous to handle.

In various embodiments, a magnesium compound may be uniquely utilized inconnection with treatment of water for potable use. For example, therelatively low solubility of magnesium compounds, such as magnesiumhydroxide and/or magnesium oxide, may have generally dissuaded the useof magnesium compounds for the treatment of potable water. For example,the relatively low solubility of magnesium compounds may have given riseto concerns about increased turbidity, increased total suspended solidsin the water and/or deleterious effects on filtration processes.Consistent with some embodiments, magnesium compounds may be utilized inconnection with the treatment of potable water without undesirablycontributing to the turbidity of the water, undesirable levels of totalsuspended solids in the water, and/or may not excessively negativelyimpact filtration, or may even improve filtration efficiency. In someembodiments, magnesium compounds having a relatively high reactivity maybe utilized in connection with the treatment of potable water. In someembodiments, magnesium compounds, such as Brucite and/or otherrelatively lower reactivity magnesium compounds may be suitably utilizedfor achieving certain results. Further, in some embodiments, relativelyhigh reactivity magnesium compounds and relatively lower reactivitymagnesium compounds may be used together to achieve a particular effectin treating the water. For example, a relatively high reactivitymagnesia and a relatively low reactivity magnesia may be combined whenit is desirable to have both a high dissolution effect (e.g., which maysupplement soluble Mg+2, OH— and increase pH facilitating flocculation),but also have sufficient particulate magnesia of either high and/or lowreactivity to facilitate adsorption of certain contaminants. Therelatively low reactivity magnesia may come from the group of compoundsincluding Brucite (naturally occurring Mg(OH)2) and/or Magnesite(naturally occurring MgCO3), both of which may be in the family ofmagnesia compounds.

In some embodiments of the present disclosure, the use of magnesiumcompound in connection with the treatment of potable water (i.e., thetreatment of water for potable use) may provide for improvements inflocculation performance and may also provide pH control and/oralkalinity control for the treated potable water. In some embodiments,the use of magnesium compound in connection with the treatment ofpotable water may allow similar and/or improved turbidity removal fromgravity sedimentation while utilizing less flocculation aiding metalsalts. In some embodiments, the use of magnesium compound in connectionwith the treatment of potable water may allow similar and/or improvedremoval of dissolved organic compounds, or total organic compounds whileutilizing less flocculation aiding metal salts. In some embodiments, theuse of magnesium compounds in connection with potable water treatmentmay provide a permanent hardness addition to the water to achieve adesired level of hardness in the treated potable water. In someembodiments, the use of magnesium compounds in connection with thetreatment of potable water may allow a desired pH and/or alkalinity tobe achieved, which may, for example, reduce or eliminate the need forchemical additions, such as caustic soda or lime, for pH and/oralkalinity control. Accordingly, in various embodiments, magnesiumcompounds may be used in connection with potable water treatment toachieve various results and/or synergistic performance improvements.

As generally discussed above, in an implementation, an effective amountof a magnesium compound may be added to supply water that is to betreated. Treating the supply water may be for the purpose of achievingpotable water standards, e.g., which may allow the treated water to bedistributed for residential or domestic use, or otherwise suitable foruse and/or consumption by individuals. The method may also includeadding an effective amount of a flocculation aiding metal salt to thesupply water. One or more contaminants may be removed from the supplywater to provide the treated water.

For example, and referring also to FIG. 1, as example embodiment of awater treatment system for treating potable water (e.g., for treatingsupply water to provide potable treated water) is generally shown.Supply water 10, which is to be treated, may include any suitable sourceof water. For example, supply water 10 may include surface water fromlakes, rivers, reservoirs, or the like. Similarly, supply water 10 mayinclude ground water, such as from wells, aquifers, or the like. Variousother suitable sources of supply water 10 may also be utilized. One ormore coagulants may be added to supply water 10 at coagulation addition12. In general, and as will be described in greater detail below, theone or more coagulants may aggregate at least a portion of the suspendedand/or dispersed contaminants within supply water 10, such that theaggregated contaminants may form larger particles that may be separatedfrom supply water 10 via various contaminant removal mechanisms. In anexample embodiment, supply water 10 including the added coagulants maybe mixed in flocculation process 14. In flocculation process 14, thecoagulants may be effectively mixed with supply water 10 andcontaminants within supply water 10 may be allowed to at least partiallycoalesce or aggregate to form larger particles.

With continued reference to FIG. 1, consistent with the illustrativewater treatment process, following flocculation 14, the water beingtreated may undergo sedimentation/sludge removal 16. Duringsedimentation/sludge removal 16 the heavier and/or larger aggregatedand/or flocculated contaminants may settle out from the water beingtreated as sediment or sludge. Clear water (e.g., water from which theaggregated and/or flocculated contaminants have settled out) from thesedimentation/sludge removal process 16 may be provided to filtrationprocess 18. Filtration process 18 may utilize one or more physicaland/or biological filtration processes to remove at least a portion ofremaining contaminants from the water received from thesedimentation/sludge removal process 16. The filtered water may beprovided to filtered/treated water storage 20, which may include one ormore storage tanks or reservoirs and/or a distribution system forproviding the treated potable water to individuals for potable use. Insome embodiments, the filtered water may undergo disinfection and/orfluoridation, e.g., to ensure the water is free from any potentiallyharmful residual contaminants and/or to add any desired additions to thewater. Further, in some embodiments, sludge and/or sediment collectedduring the sedimentation/sludge removal process 16 may be collected andat least partially dewatered or dried during sludge thickening process22. The at least partially dewatered sludge and/or sediment 16 may beremoved for disposal, e.g., in a landfill or via horticultural use.

The magnesium compound and the flocculation aiding metal salts may beadded in the coagulation addition process 12. For example, the effectiveamount of the magnesium compound may be added to supply water 10 atcoagulation addition 12. Further, in an example embodiment, theeffective amount of the flocculation aiding metal salt may also be addedto supply water 10 at coagulation addition 12. In an illustrativeembodiment, the magnesium compound may include one or more of magnesiumhydroxide and magnesium oxide, as well as some mixture of magnesiumhydroxide and magnesium oxide. In some embodiments, mixtures ofrelatively high reactivity magnesium compounds (e.g., as may bediscussed in greater detail below) may be using in combination with oneor more relatively lower reactivity magnesium compounds, such as Bruciteor magnesite. Further, the flocculation aiding metal salts may includeone or more of alum, ferrous sulfate, ferric sulfate, ferrous chloride,and ferric chloride. Various additional and/or alternative coagulantsand/or flocculation aids may be utilized.

In general, flocculation aiding metal salts may be utilized as a primaryagent for the removal of contaminants from supply water that is to betreated for potable use. For example, often turbidity in supply water,which may be desirably removed to provide potable water, may includesilts, sand or silica, clays or alumino-silicates, and natural organicmatter (“NOM”). These materials may be at least partially negativelycharged in water at near neutral pH. The flocculation aiding metalsalts, as well as some other flocculation aiding agents, may often be atleast partially positively charged at near-neutral pH. In someembodiments, the flocculation aiding agents (including the flocculationaiding metal salts) may form mixed particulates of the at leastpartially positively charged flocculation aiding agents and the at leastpartially negatively charged contaminants, thereby forming enmeshedfloc. Various additional and/or alternative mechanisms may also beinvolved in the flocculation of contaminants within the supply waterthrough the use of the flocculation aiding metal salts.

In some embodiments, the magnesium compounds may be used to improve theremoval of unwanted or undesirable raw water constituents, whilereducing or eliminating the consequences of using the flocculationaiding metal salts, polymer flocculation aiding agents, as well as otherflocculation aiding agents, on the quality of the resultant treatedwater, as well as on the potable water infrastructure, through which thetreated potable water may be distributed to end users for consumption.For example, flocculation aiding metal salts may reduce the pH of thewater being treated, and may reduce the alkalinity of the water beingtreated. As such, the flocculation aiding metal salts may result in aneeded increase in the use of pH-dependent disinfection chemicals.Further, the flocculation aiding metal salts may increase thecorrosivity of the water being treated, which may result in an increasein the need for corrosion control chemicals. Further, in some situationsthe use of flocculation aiding metal salts may increase filtrationrequirements and loading, etc. associated with removal of contaminantsfrom the water being treated.

An effective amount of the magnesium compound added to supply water 10may facilitate the removal of total organic carbon (“TOC”), as well asthe removal of other contaminants. For example, in some embodiments, theeffective amount of the magnesium compound may reduce and/or minimizethe pH depression caused by the flocculation aiding metal salts.Further, in some embodiments, the effective amount of the magnesiumcompound may facilitate the formation of metal hydroxides AlOHx, FeOHx,and/or Mg(OH)₂, which may enhance flocculation and sedimentation ofsettleable solids, containing total suspended solids (“TSS”) or TOC, inthe water. For example, at least partially positively charged metalhydroxides and the at least partially negatively charged contaminantparticles may form an enmeshed floc that may facilitate separation fromthe water being treated. Furthermore, in some embodiments, theadsorption of positive cations, such as Mg⁺², onto negatively chargedparticles of contaminants may result in a charge reduction, and therebyprovide less resistance to flocculation of the negatively chargedcontaminants. Additionally, in some embodiments, an increased saltconcentration in the water being treated may result in a reduction inthe electrical double layer, which may facilitate removal of contaminantparticles from the water being treated. As generally discussed above,the effective amount of the magnesium compound may further enhance thequality of treated water in that the treated water may requirerelatively lower amounts of chemicals and polymers used fordisinfection, scale prevention, and reducing water corrosivity. Thereduction in the use of the chemicals and polymers may thereby reduceany potentially harmful by-products that such chemicals may cause.Accordingly, in an embodiment, adding the effective amount of themagnesium compound and the flocculation aiding metal salt may be basedupon, at least in part, a desired removal of TSS, TOC, dissolved organiccarbon (“DOC”), and/or NOM.

In addition improving TOC, DOC and NOM removal in conjunction withflocculation aiding metal salts, in some embodiments the effectiveamount of the magnesium compound may facilitate and/or aid in theremoval of inorganic constituents, such as arsenic, selenium, or thelike. For example, the ability to remove, and/or aid in the removal of,inorganic constituents may be a function of residual magnesium hydroxideand/or magnesium oxide solids that may be on a physical filter (e.g.during filtration 18). For example, in some situations the residualmagnesium compound may complex aluminum from alum (which may be utilizedas a flocculation aiding metal salt). Such a magnesium-aluminum complexmay absorb and/or adsorb the inorganics such as arsenic, selenium andother potentially toxic metals. Other processes may be involved and/orresponsible for the removal of inorganic materials from the water beingtreated. Removal of inorganic materials resulting from the use ofmagnesium compounds for the treatment of potable water may provide asignificant benefit to potable water treatment plants, e.g., as stricterEPA guidelines may be established to minimize such contaminants fordrinking water.

As generally discussed above, magnesium compounds may be utilized incombination with one or more flocculation aiding metal salts tofacilitate contaminant removal from water that may be treated forpotable use. For example, an effective amount of the magnesium compoundmay be added to the supply water to facilitate, promote, and/or improveflocculation efficiency and effectiveness. In some such embodiments, theflocculation efficiency and/or effectiveness may be improved to allowthe amount of flocculation aiding metal salts to be reduced, e.g., ascompared to the amount that may be required for treating potable waterwithout the use of the magnesium compounds. Further, in someembodiments, the effective amount of the magnesium compound mayadditionally and/or alternatively compensate for at least a portion ofthe pH reduction in the water being treated as a result of the additionof the flocculation aiding metal salts and/or compensate for at least aportion of the alkalinity depression in the water being treated as aresult of the addition of the flocculation aiding metal salts. In somesuch embodiments, the need for additional and/or separate chemicaladditions to the water to compensate for the reduced pH and/or thedepressed alkalinity may be reduced and/or eliminated. Further, in someembodiments, the effective amount of the magnesium compound mayfacilitate and/or promote the removal of inorganic materials from thewater being treated. For example, the effective amount of the magnesiumcompound may facilitate and/or promote the removal of arsenic and/orselenium, and/or various other potentially toxic metals from the waterbeing treated.

In an embodiment, the effective amount of the magnesium compound and theone or more flocculation aiding metal salts may facilitate and/orpromote removing organic materials, which may affect color, odors andtaste, from the supply water. Example of such organic materials mayinclude, but are not limited to tannic compounds and/or humic compounds.Organic acids, such as tannic acids and/or humic acids, may be abreakdown product of, or be the result of, decomposed plant matter. Suchcontaminants have been known to result in unwanted taste, coloration andturbidity in potable water, especially in U.S. geographic regions suchas South Florida, even after final filtration from the potable waterplant into drinking reservoirs. An effective amount of the magnesiumcompound may be added to the water being treated, along with aneffective amount of the one or more flocculation aiding metal salts,and/or polymer treatment agents, to reduce and/or eliminate organicmaterials in the treated potable water including tannins, tannic acid,humus, humic acid, and other similar organics that may impartundesirable taste or color. In some implementations the removal oforganics, and/or the removal of inorganics, may be promoted and/orimproved by the further addition of an oxidizer, such as hypochloritesalts, percarbonate salts, peroxides, nitrates and associated salts, orsimilar, to the supply water.

Adding the effective amount of the magnesium compound may include addingthe magnesium compound to the supply water prior to adding theflocculation aiding metal salt. Adding the magnesium compound prior toadding the flocculation aiding metal salt may include adding themagnesium compound at a location that is upstream in the water treatmentprocess relative to a location at which the flocculation aiding metalsalt is added. For example, the magnesium compound may be added upstreamof, or prior to, the addition of acidic, or low pH, products such as,but not limited to, flocculation aiding metal salts. In someembodiments, the magnesium compound may be added to the supply water andmay be dosed to reduce and/or to minimize the potential contribution tofinished water turbidity or suspended solids resulting from themagnesium compound. In some embodiments, adding the magnesium compoundto reduce and/or minimize the turbidity or suspended solids in thefinished, or treated water, may include adding the magnesium insufficient quantities such that the turbidity and/or suspended solids inthe finished water may be minimized and/or reduced. In some embodiments,adding the magnesium compound to reduce and/or minimize the turbidity orsuspended solids in the finished water may include adding the magnesiumcompound sufficiently upstream in the water treatment process to allowsufficient dissolution or collection (e.g., via sedimentation and/orfiltration) of the magnesium compound to reduce and/or minimizeturbidity or suspended solids in the finished water. In an embodiment,adding the magnesium compound prior to adding the flocculation aidingmetal salts may include adding the magnesium compound at an upstreamlocation within coagulant addition process 12 relative to the locationat which the flocculation aiding metal salt is added. In someembodiments, adding the effective amount of the magnesium compound mayinclude adding the magnesium compound generally along with adding theflocculation aiding metal salt. For example, the magnesium compound maybe added at generally the same location within the coagulant additionprocess 12 as the flocculation aiding metal salts. Still further, insome embodiments, the magnesium compound may be added to the supplywater after the addition of the flocculation aiding metal salt.

In some embodiments, the quality and reactivity of magnesium compoundmay be selected to provide desirable performance. For example, in somesituations it may be possible that any un-dissolved magnesium compoundthat accumulates in a filter utilized in connection with potable watertreatment may continue to dissolve and may improve capture in thefilter. In some situations, a relatively less reactive grade ofmagnesia, such as Brucite, may not provide a comparable rate ofdissolution, and thus may exhibit more characteristics of fouling thanmight be achieved with relatively more reactive grades of magnesia.Illustrative examples of relatively more reactive magnesium compound mayinclude Thioguard® and Magox® brands of magnesium hydroxide andmagnesium oxide available from Premier Magnesia, LLC. The mechanisms forimproved performance associated with relatively higher reactivitymagnesium compounds may, in some implementations, be based upon, atleast in part, the characteristics of the matrix formed by the media,the filter, the magnesia and the metal salt, and may account for thebetter overall performance. However, in some implementations lessreactive grades of magnesia may be acceptably utilized to varyingdegrees of efficacy. In some implementations, relatively less reactivegrades of magnesium compounds may be used in conjunction with relativelyhigher reactivity grades of magnesium compounds to achieve a specificresult.

In an example embodiment, magnesium compounds (e.g., magnesium oxideand/or magnesium hydroxide) may be utilized having a relatively highdegree of purity. In an example embodiment, magnesium compounds may beprovided having an alkaline magnesium oxide and/or alkaline magnesiumhydroxide purity of between about 85% to about 100% pure alkalinemagnesium oxide and/or magnesium hydroxide. In an illustrativeembodiment, a magnesium compound may be provided having an alkalinemagnesium oxide and/or alkaline magnesium hydroxide purity of betweenabout 91% to about 98% pure alkaline magnesium oxide and/or magnesiumhydroxide.

In some embodiments, the stability of the magnesium hydroxide may begenerally related to the ability of a magnesium hydroxide slurry tomaintain pumpability while minimizing solids residue that may accumulatein a storage and/or transportation tank (e.g., rail tank, tanker truck,etc.), which may become difficult to re-suspend. Accordingly, thestability of the magnesium hydroxide may be indicative of the ability ofa magnesium hydroxide slurry to withstand transportation and storage,while remaining susceptible to dispensing, as through pumping. In anexample embodiment, the stability of a magnesium hydroxide slurry may bequantified using the stabilized residuals test (“SRT-Tap Test”). Ingeneral, the SRT-Tap test may assess the solids settling stability ofmagnesium hydroxide suspensions. According to an embodiment, an eightfluid ounce test bottle may be filled with a magnesium hydroxide slurry.The magnesium hydroxide slurry may be retained in the test bottle for afourteen hour period, with the test bottle maintained in an uprightposition. After fourteen hours, sediment collecting in the bottom of thetest bottle (e.g., as a result of magnesium hydroxide falling out ofsuspension) may be evaluated. The test bottle containing the slurryand/or any collected sediment may be vigorously shaken in a horizontalorientation of the test bottle for fifteen seconds, and the slurry maythen be poured out of the test bottle. The test bottle may subsequentlybe filled with approximately an inch and a half of water, which may beswirled within the bottle to remove slurry film from the side of thebottled. The water may be poured from the test bottle and the testbottle may be inverted to drain for fifteen minutes. A differencebetween the post draining weight of the test bottle and an initialweight (e.g., prior to initially filling the test bottle with magnesiumhydroxide slurry) may be determined. According to various embodiments, asuitable magnesium hydroxide may provide an SRT-Tap test value ofbetween about 1 milligram and about 50 grams. In some embodiments, asuitable magnesium hydroxide may provide an SRT-Tap test value ofbetween about 0.1 gram to about 50 grams. In an embodiment, a suitablemagnesium hydroxide may provide an SRT-Tap test value of between about 1gram to about 50 grams. In an example embodiment, a suitable magnesiumhydroxide may provide an SRT-Tap Test value of between about 1 gram andabout 20 grams. In a particular embodiment, a suitable magnesiumhydroxide may provide an SRT-TAP Test value of between about 1 gram andabout 20 grams, with an average value of about 10 grams.

In some embodiments, a magnesium compound may include magnesiumhydroxide exhibiting a caustic magnesia activity (“CMA”) neutralizationtime of between about 50 seconds to about 1440 minutes using 1.0N aceticacid and a magnesium hydroxide content of between about 10% to about100%. In some embodiments, a magnesium compound may include magnesiumoxide exhibiting a caustic magnesia activity neutralization time ofbetween about 30 seconds to about 3600 seconds using 1.0N acetic acidand a magnesium oxide content of between about 10% to about 100%. Insome embodiments, a magnesium compound may include magnesium oxideexhibiting a caustic magnesia activity neutralization time of betweenabout 50 seconds to about 1000 seconds using 1.0N acetic acid and amagnesium oxide content of between about 10% to about 100%. In anembodiment, the magnesium compound may be provided exhibiting a causticmagnesia activity neutralization time of between about 50 seconds toabout 200 seconds using a 1.0N acetic acid and a magnesium oxide and/ormagnesium hydroxide content of between about 10% to about 100%. In aparticular example embodiment, the magnesium compound may be providedexhibiting a caustic magnesia activity neutralization time of about 125seconds using a 1.0N acetic acid and a magnesium oxide and/or magnesiumhydroxide content of between about 10% to about 100%.

In an embodiment, the magnesium compound may be provided having aparticle size that may provide an enhanced specific surface area(“SSA”). For example, generally, a magnesium compound having a smallerparticle size may enhance the overall specific surface area of themagnesium compound (e.g., which may include magnesium oxide and/ormagnesium hydroxide). In an embodiment, a magnesium compound may includea magnesium hydroxide exhibiting a particle size of between about 0.1micron to about 50 micron. In some embodiments, a magnesium compound mayinclude magnesium oxide exhibiting a particle size of between about 0.1micron to about 30 micron. For example, in an embodiment, the magnesiumcompound may include a magnesium oxide and/or magnesium hydroxide havinga particle size of between about 1 micron to about 20 microns. In oneillustrative embodiment, the magnesium compound may include a magnesiumoxide and/or magnesium hydroxide having an average particle size ofabout 10 micron.

In addition to the average particle size, the magnesium compound may beprovided having a particle size distribution that may improve thestability of a slurry produced using the magnesium compound. Asgenerally discussed above, a higher degree of stability of a slurryproduced using the magnesium compound may generally relate to theability to maintain pumpability of the slurry while minimizing solidsresidue that may accumulate in a storage and/or transportation tank. Insome situations, a relatively more narrow particle size distribution ofthe magnesium compound may increase the stability of a slurry producedusing the magnesium compound. In an embodiment, particle size andparticle size distribution may be measured and/or controlled usingscreen analysis and a particle size distribution analyzer.

In an embodiment, a magnesium compound may be provided having a desiredreactivity. A magnesium compound having a relatively higher reactivitymay provide more complete and efficient use within a desiredapplication, and may, in some instances, at least partially offset arelatively low solubility that may be associated with magnesiumcompounds such as magnesium oxide and/or magnesium hydroxide. In anembodiment, specific surface area (“SSA”) of the magnesium compound maybe correlated to reactivity, e.g., in which a relatively higher specificsurface area may be correlated to a relatively higher reactivity. Insome embodiments, a magnesium compound may include magnesium hydroxideexhibiting a specific surface area of between about 9 m²/g to about 200m²/g. For example, in an example embodiment, a magnesium compound mayinclude magnesium hydroxide having a specific surface area in the rangeof between about 9 m²/gram to about 50 m²/gram. In one particularembodiment, a magnesium hydroxide may include a specific surface area ofabout 12 m²/gram. In some embodiments, a magnesium compound may includemagnesium oxide exhibiting a specific surface area of between about 9m²/g to about 300 m²/g, or greater. For example, in an exampleembodiment, a magnesium compound may include magnesium oxide having aspecific surface area in the range of between about 9 m²/gram to about150 m²/gram, or greater.

While magnesium compounds having various different characteristics (suchas purity, SRT-Tap Test values, CMA, particle size, and SSA) have beendescribed, it will be understood that such characteristics, andrepresentative values, are provided for the purpose of illustration andexample. Consistent with the present disclosure, magnesium oxide and/ormagnesium hydroxide compounds having different characteristic values maybe utilized in connection with treating potable water to varying degreesof efficacy, either individually or in combination.

In some embodiments, combinations of magnesium compounds havingdifferent reactivities may be utilized in connection with the treatmentof potable water. For example, in an embodiment relatively highreactivity magnesium compounds and relatively lower reactivity magnesiumcompounds may be used together to achieve a particular effect intreating the water. In some embodiments, the combination of magnesiumcompounds having different reactivities may achieve synergisticbenefits. For example, combinations of magnesium compounds havingdiffering reactivities may be added to water being treated to aid inremoving a particular contaminant from the water. In some suchembodiments, the different magnesium compounds having differentreactivities may provide a synergistic result, for example, in terms ofremoving particular contaminants, controlling pH or alkalinity of thepotable water, etc.

The method may further include adding an effective amount of a polymercontaminant removal aid including one or more ofpolyepichlorohydrin-dimethylamine, polyamine,polydiallyl-dimethylammonium chloride (polyDADMAC), polyacrylate,polyamide, a Mannich polymer, and polyacrylamide. For example, and asgenerally described above, organic solids, which may often be measuredand/or reported as TOC, may be removed, at least in part, through theaddition of flocculation aiding metal salt such as alum (e.g., aluminumsulfate), ferrous chloride, ferric chloride, ferrous sulfate, ferricsulfate, or other metal chlorides or salts to promote flocculation andcoagulation of solids. The flocculated and/or coagulated solids may thenbe removed through the process of sedimentation 16 or filtration process18. An effective amount of the magnesium compound may be added to thewater being treated (e.g., supply water 10). For example, the magnesiumcompound may be added to the water being treated upstream relative tothe addition of the flocculation aiding metal salt. The addition of theeffective amount of the magnesium compound may reduce, and/or prevent,the depletion of alkalinity from water and/or may reduce, and/orprevent, the depression of pH. In such an implementation, the additionof the magnesium compound may increase processing efficiency and/orreduce corrosiveness of the water, which may be, at least in part,attributed to the use of the flocculation aiding metal salts fortreating the water. In some implementations, magnesia may similarly beused in connection with polymers (such as, but not limited to,polyepichlorohydrin-dimethylamines, polyamines,polydiallyl-dimethylammonium chloride (polyDADMAC), polyacrylates,polyamides, Mannichs, polyacrylamides, etc.) which may also be used inconnection with water treatment. Such polymers, or polymeric compounds,may aid the coagulation/flocculation process, for example, by addingpositively or negatively charged substrates to facilitate theagglomeration of oppositely charged contaminants and flocculation aids.Accordingly, in some embodiments, an effective amount of a polymerflocculating or solids conditioning aid may be added to the watersupply. In some such embodiments, the further combination of magnesiumcompounds and polymer coagulation/flocculation aids may provide improvedcontaminant removal. Further, in some embodiments, the use of magnesiumcompounds in combination with polymer coagulation/flocculation aids mayreduce the quantity of polymer coagulation/flocculation aids that may berequired to achieve a similar contaminant removal (e.g., as compared toa quantity of polymer coagulation/flocculation aid that may be utilizedin the absence of the magnesium compound).

Adding the magnesium compound may include adding an admixture of themagnesium compound and an alkaline earth metal compound. For example, inan embodiment, the effective amount of the magnesium compound mayincrease divalent cation concentration in the water, which may improvewastewater treatment, after the potable water has been used byindividuals and/or businesses. For example, increasing the divalentcation concentration may improve wastewater treatment in terms ofclarification, sedimentation, dewatering etc., by counteracting theimbalances created by sodium and other monovalent compounds that may bedischarged to the sewer system. In an embodiment, adding the magnesiumcompound in admixture with one or more alkaline earth metal compounds,such as beryllium compounds, other magnesium compounds, calciumcompounds, strontium compounds, barium compounds, and/or radiumcompounds, may facilitate increasing the divalent cation concentrationsin the treated potable water.

Adding the effective amount of the magnesium compound includes measuringa quality of the treated water. For example, as generally discussed,flocculation aiding metal salts, as well as various other agents used inthe treatment of potable water may impact various water qualityattributes, e.g., which may render such quality attributes lessdesirable. Additionally, the supply water may have various qualityattributes that may be less desirable, e.g., even prior to treatmentwith flocculation aiding metal salts and/or other agents. As such, theeffective amount of the magnesium compound may at least partiallycompensate for less desirable water quality attributes. For example, thequality of the treated water may include one or more of an alkalinity ofthe treated water and a pH of the treated water. Adding the effectiveamount of the magnesium compound may include measuring the pH and/oralkalinity of the treated water to determine the effective amount of themagnesium compound, e.g., which may at least partially provide adesirable pH and/or alkalinity in the treated water.

As generally discussed above, the flocculation aiding metal salt, aswell as other agents used to treat the potable water, may deplete thealkalinity of the treated water. In an embodiment, an anticipatedalkalinity depletion associated with adding the flocculation aidingmetal salt may be determined. Additionally/alternatively an anticipatedpH decrease associated with adding the flocculation aiding metal saltmay be determined. One or more of the determined anticipated alkalinitydepletion and/or pH decrease associated with adding the flocculationaiding metal salt may allow an effective amount, and/or an initialanticipated effective amount, of the magnesium compound to bedetermined. For example, the effective amount, and/or the initialanticipated effective amount of the magnesium compound may be basedupon, at least in part, an amount of the magnesium compound offsettingat least a portion of the anticipated alkalinity depletion.

The effective amount of the magnesium compound may be adjusted basedupon, at least in part, the measured quality of the treated water. Forexample, the initial anticipated effective amount of the magnesiumcompound may be added to the supply water based upon, at least in part,an anticipated alkalinity depletion and/or pH decrease. Subsequently,the actual alkalinity, pH, and/or another water quality attribute of thetreated water may be determined. The effective amount of the magnesiumcompound added to the supply water may be adjusted from the initialanticipated effective amount, e.g., to achieve and/or more closelyapproach a desired water quality attribute.

In an embodiment, the magnesium compound may be added in sufficientquantities to the finished potable water to increase pH and/oralkalinity levels in the wastewater collection system that may receivethe potable water after it has been used by homes or businesses. In anexample, the pH and/or alkalinity levels present in the waste water maybe sufficient to prevent and/or reduce such issues as odors, corrosion,FOG, etc once the water passes to the wastewater collection system. Inaddition/as an alternative to compensating for any depletion in thealkalinity of the treated water resulting from the use of theflocculation aiding metal salt, in an embodiment the alkaline value ofthe potable water to be distributed may be increased to be greater thanthe alkaline value of the supply water. In some such embodiments, thetreated potable water may have a greater value in terms of wastewatertreatment. That is, once the treated potable water has been used byconsumers and passed into the wastewater collection system, theresultant wastewater may have a higher alkaline value than the initialsupply water, and thereby may render the wastewater more resistant toproblems in wastewater treatment such as odors, corrosion, and acidproduction from biological treatment.

In an embodiment, the magnesium value of the potable water to bedistributed may be greater than before treatment, and therefore may havea greater value in terms of health benefits to the consumers of thepotable water. For example, many individuals may be at least partiallydeficient in nutritional magnesium. In a similar manner as otherbeneficial additions, such a fluoride, the effective amount of magnesiumcompound may provide beneficial nutritional magnesium to individuals whodrink the treated potable water. In this regard, there is suggestionand/or evidence that appropriate nutritional magnesium intake mayprevent Type 2 diabetes, prevent osteoporosis, reduce migraineheadaches, reduce cardiovascular disease, and/or lower blood pressure.In some embodiments, the effective amount of the magnesium compound mayprovide the potential for one or more such health benefits toindividuals consuming the treated potable water. In an embodiment, suchan effective amount of the magnesium compound may be based upon, atleast in part, a measured effective nutritional magnesium quality of thetreated potable water. Selection of the quality of magnesia may be basedin part on the quantity of magnesium desired in the treated water. Insome situations, lower reactivity forms of magnesia may be capturedduring sedimentation or filtration, which may prevent the desiredmagnesium fortification from being achieved through magnesia introducedto the treatment process. Magnesium may still be added to the finishedwater in the forms of more highly soluble salts, including but notlimited to magnesium chloride, magnesium sulfate, magnesium citrate,etc.

In an embodiment, the quality of the treated water may include acorrosivity of the treated water as indicated by a Langelier Index ofthe treated water. For example, in an implementation, the magnesiumcompound may be utilized for treating supply water, at least in part tocontrol and/or reduce the corrosivity of the treated water. Accordingly,in an implementation, supply water may be treated including adding aneffective amount of a flocculation aiding metal salt to the supply waterand removing one or more contaminants from the supply water. Treatingthe supply water may provide treated potable water. Further, acorrosivity associated with the treated potable water may be determined.An effective amount of a magnesium compound may be added to the supplywater based upon, at least in part, the determined corrosivityassociated with the treated potable water to achieve a desired reducedcorrosivity associated with the treated potable water. For example, thedetermined corrosivity associated with the treated potable water may bebased upon, at least in part, one or more of a quality of the supplywater, a corrosivity resulting from the flocculation aiding metal salts,and/or one or more other agents utilized in treating the potable water.As generally described above, corrosivity of the water may bequantified, or represented, using the Langelier's Index. Accordingly, inan embodiment, determining the corrosivity associated with the treatedpotable water may include determining a Langelier's Index associatedwith the treated potable water. Further, the effective amount of themagnesium compound added to the supply water and/or to the treatedpotable water may include an amount sufficient to provide an Langelier'sIndex value associated with the treated potable water that may indicatea desired degree of corrosivity, for example, a relatively low level ofcorrosivity associated with the treated potable water. In someembodiments, the reduction in corrosivity associated with the treatedpotable water may eliminate, or reduce, the need for corrosioninhibiting agents, such as phosphates, which may conventionally beutilized in connection with treated water. Accordingly, in someembodiment, the use of corrosion control agents, such as phosphates,polyphosphates, phosphonates, may be optimized and/or reduced basedupon, at least in part, the corrosivity of the water and the effectiveamount of magnesium compound added to the supply water.

As generally described above, the treatment of the supply water toprovide treated potable water may include removing one or morecontaminants from the supply water to provide treated water. Removingone or more contaminants from the supply water may include one or moreof flocculation, coagulation, sedimentation and filtration. For example,one or more contaminants may be removed from the water via theflocculation process 14 and/or the sedimentation process 16. Further,and as also described with respect to FIG. 1, removing one or morecontaminants may include filtration (e.g., via filtration process 18).In some embodiments utilizing filtration to remove one or morecontaminants, the performance of the filtration process may be evaluatedin terms or contaminant removal performance and maintenance.Conventionally, because magnesium hydroxide may have a relatively lowsolubility, magnesium hydroxide has generally been dismissed as analkaline modifier in potable water treatment, due to potential increasesin TSS and turbidity, or clogging and scaling of filters. Uniquely,consistent with an aspect of the present disclosure, magnesium compoundsmay be used to improve the performance of the filters, both in terms ofreduced final TSS and turbidity, but also in terms of backwashrequirements for filtration. In some embodiments, at least a portion ofany residual magnesium compound captured in a filter may be recycledfrom a filter element back into the supply water (e.g., as generallyindicated by arrow 24 in FIG. 1). For example, when a filter element isbackwashed, e.g., to remove any build-up of material that may reduce theperformance of the filter, at least a portion of the backwash, which mayinclude residual magnesium compound, may be returned to specific partsof the treatment process. Returning at least a portion of the backwash(e.g., recycling residual magnesium compound) to specific parts of thetreatment process may enhance the flocculation and sedimentationprocesses preceding filtration, and may minimize and/or reduce therequirements of the magnesium compounds and/or the flocculation aidingmetal salts to the raw supply water.

In some embodiments, removing one or more contaminants from the supplywater may include using a bio-filtration process. Bio-filtrationprocesses may include removing organic material from the water using abiological process. In such an embodiment, adding the effective amountof the magnesium compound may include adding an effective amount of themagnesium compound to the supply water to improve the performance of thebio-filtration process. As generally mentioned bio-filtration mayinclude biological removal of contaminants through a bio-filter orbio-media. In such bio-filtration processes, organic material may beremoved biologically, and the magnesium compound may serve as a nutrientand cationic enhancement to the microorganisms and/or to the structureof the biological matrix, which may thereby improve biologicalperformance. In addition/as an alternative to improving biologicalperformance, the magnesium compound may reduce and/or minimize problemsassociated with sloughing and clogging of biomass. Further, in someembodiments, the magnesium compound may serve to make the organics moredigestible.

Consistent with the foregoing, in some implementations, the magnesiumcompound may be optimized not only for flocculation aiding metal saltuse but may also be optimized for filtration performance. In someimplementations, the magnesium compound may be added in sufficientquantities to the water being treated to improve the performance of thefilters, whether stratified media or membrane. The magnesium compoundmay be dosed sufficiently to actively reduce the required quantities offlocculation aiding metal salts, to reduce inorganic and organic loadingto the filtration process, to reduce the impacts of scaling/fouling,and/or to reduce or minimize backwash or replacement rates of media andfilters. In implementations utilizing bio-filtration, the magnesiumcompound may be added in sufficient quantities to improve performance ofthe bio-filters in terms of organics removal from the water stream andoverall health of the biomass.

Consistent with the foregoing, in some implementations, processing thesupply water to provide potable water may include removing constituents(such as contaminants) from the water that may be harmful. Processingthe supply water to provide potable water may also include removingother constituents that may impart undesirable color, taste, turbidityor odor. The removed constituents may be in the form of dissolved solidsor gases, suspended solids or gases, miscible or immiscible liquids, andmay be organic and/or inorganic in nature. These constituents may bemeasured as Total Organic Carbon (“TOC”), Total Dissolved Solids(“TDS”), and Total Suspended Solids (“TSS”). In some situations,specific constituents such as minerals may be identified in more detail.

According to various embodiments and implementations, the presentdisclosure may utilize magnesium compounds in combination withflocculation aiding metal salts in the treatment of water to make thewater suitable for potable use. In some embodiments, the utilization ofthe magnesium compounds may improve the effectiveness of flocculationaiding metal salt use in the treatment of potable water. Consistent withsome embodiments, the magnesium compound and the flocculation aidingmetal salt may be dosed to achieve optimal and/or improved TSS and/orTOC removal, and may achieve a reduction in turbidity. In someembodiments, the magnesium compound may be added in sufficientquantities to reduce or eliminate aluminum and/or iron in the finishedpotable water and/or in the sludge or sediment recovered during thetreatment process. Similarly, the magnesium compound may also reduce oreliminate the need for polymer additives.

Often in other areas of water treatment, such as wastewater treatment,there has been suggestion that flocculation performance may deteriorateas pH rises. However, consistent with the present disclosure, the use ofmagnesium compounds and the resultant increase and/or stabilization ofpH has been found to improve flocculation performance. It may bepossible that according to prior processes, which realized a decrease inflocculation performance as pH rises, pH may have been modified usingcaustic soda or lime. In the case of caustic soda use, for example, thesodium added to the system when using sodium hydroxide may bedeleterious to flocculation and sedimentation. Consistent with thepresent disclosure, it may be the case that because of the specificparticulate and cationic properties, magnesium compounds used for pHelevation in conjunction with the flocculation aiding metal salts maylead to improved performance of the system for flocculation andsedimentation.

In some embodiments, the magnesium compounds may be added in sufficientquantities to increase and/or optimize metal hydroxide formation.Further, in some implementations, magnesium compounds may be added insufficient quantities to reduce the required amount of disinfectionchemicals necessary to achieve potable water standards. As generallydescribed above, the magnesium compounds may be added to the water beingtreated in sufficient quantities, and along with one or moreflocculation aiding metal salts, polymers, and/or one or more oxidizers,in order to remove and/or reduce organics or undesirable inorganics suchas arsenic or selenium. Further, in some implementations, the magnesiumcompounds may be added to the water being treated in sufficientquantities to alter the Langelier index to indicate the potable waterproduced may be less corrosive.

In addition, as an alternative to possible potable water treatmentperformance increases, in some implementations magnesium compoundsutilized in connection with the treatment of potable water may providevarious health benefits. For example, increasing the residual magnesiumcontent in potable water, which is valued by the WHO (World HealthOrganization) for providing specific health benefits, may provide somereduction in heart disease and diabetes, and/or may provide other healthbenefits.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made. Accordingly, otherimplementations are within the scope of the following claims.

What is claimed is:
 1. A method comprising: adding an effective amountof a magnesium compound to supply water to be treated, wherein themagnesium compound includes magnesium hydroxide exhibiting an alkalinemagnesium hydroxide purity of between about 85% to about 100%; a causticmagnesia activity of between about 50 seconds to about 1440 minutes; aparticle size of between about 0.1 micron to about 50 microns; aspecific surface area of between about 9 m²/g to about 200 m²/g; and astabilized residuals test value of between about 1 milligram to about 50grams; adding an effective amount of a flocculation aiding metal salt tothe supply water; and removing one or more contaminants from the supplywater to provide treated water.
 2. The method of claim 1, wherein theflocculation aiding metal salt includes one or more of alum, ferroussulfate, ferric sulfate, ferrous chloride, and ferric chloride.
 3. Themethod of claim 1, wherein adding the effective amount of the magnesiumcompound includes adding the magnesium compound to the supply waterprior to adding the flocculation aiding metal salt.
 4. The method ofclaim 1, wherein adding the effective amount of the magnesium compoundincludes adding the magnesium compound generally along with adding theflocculation aiding metal salt.
 5. The method of claim 1, wherein addingthe effective amount of the magnesium compound includes measuring aquality of the treated water.
 6. The method of claim 5, furtherincluding adjusting the effective amount of the magnesium compound basedupon, at least in part, the measured quality of the treated water. 7.The method of claim 5, wherein the quality of the treated water includesone or more of an alkalinity of the treated water and a pH of thetreated water.
 8. The method of claim 5, wherein the quality of thetreated water includes a corrosivity of the treated water as indicatedby a Langelier Index of the treated water.
 9. The method of claim 1,further including determining an anticipated alkalinity depletionassociated with adding the flocculation aiding metal salt, and whereinthe effective amount of the magnesium compound is based upon, at leastin part, amount offsetting at least a portion of the anticipatedalkalinity depletion.
 10. The method of claim 1, further includingadding an effective amount of a polymer contaminant removal aidincluding one or more of polyepichlorohydrin-dimethylamine, polyamine,polydiallyl-dimethylammonium chloride (polyDADMAC), polyacrylate,polyamide, a Mannich polymer, and polyacrylamide.
 11. The method ofclaim 1, wherein removing one or more contaminants from the supply waterincludes one or more of flocculation, coagulation, sedimentation, andfiltration.
 12. The method of claim 11, wherein removing one or morecontaminants from the supply water includes filtration, and furtherincluding recycling a residual magnesium compound from a filter elementand recycling the residual magnesium compound into the supply water. 13.The method of claim 1, wherein adding the magnesium compound includesadding an admixture of the magnesium compound and an alkaline earthmetal compound.
 14. A method comprising: treating supply water,including adding an effective amount of a flocculation aiding metal saltto the supply water and removing one or more contaminants from thesupply water, to provide treated potable water; determining acorrosivity associated with the treated potable water; adding aneffective amount of a magnesium compound to the supply water based upon,at least in part, the determined corrosivity associated with the treatedpotable water to achieve a desired reduced corrosivity associated withthe treated potable water.
 15. The method of claim 14, whereindetermining the corrosivity associated with the treated potable waterincludes determining a Langelier's Index associated with the treatedpotable water.
 16. The method of claim 14, wherein the magnesiumcompound includes magnesium hydroxide exhibiting an alkaline magnesiumhydroxide purity of between about 85% to about 100%; a caustic magnesiaactivity of between about 50 seconds to about 1440 minutes; a particlesize of between about 0.1 micron to about 50 microns; a specific surfacearea of between about 9 m²/g to about 200 m²/g; and a stabilizedresiduals test value of between about 1 milligram to about 50 grams. 17.The method of claim 14, wherein the magnesium compound includesmagnesium oxide exhibiting an alkaline magnesium oxide purity of betweenabout 85% to about 100%; a caustic magnesia activity of between about 30seconds to about 3600 seconds; a particle size of between about 0.1micron to about 30 microns; and a specific surface area of between about9 m²/g to about 300 m²/g.
 18. The method of claim 14, wherein adding theeffective amount of the magnesium compound includes adding the magnesiumcompound to the supply water prior to adding the flocculation aidingmetal salt.
 19. The method of claim 14, wherein adding the effectiveamount of the magnesium compound includes adding the magnesium compoundgenerally along with adding the flocculation aiding metal salt.
 20. Amethod comprising: adding an effective amount of a magnesium compound tosupply water to be treated, wherein the magnesium compound includesmagnesium oxide exhibiting an alkaline magnesium oxide purity of betweenabout 85% to about 100%; a caustic magnesia activity of between about 30seconds to about 3600 seconds; a particle size of between about 0.1micron to about 30 microns; and a specific surface area of between about9 m²/g to about 300 m²/g; adding an effective amount of a flocculationaiding metal salt to the supply water; and removing one or morecontaminants from the supply water to provide treated water.
 21. Themethod of claim 20, wherein the flocculation aiding metal salt includesone or more of alum, ferrous sulfate, ferric sulfate, ferrous chloride,and ferric chloride.
 22. The method of claim 20, wherein adding theeffective amount of the magnesium compound includes adding the magnesiumcompound to the supply water prior to adding the flocculation aidingmetal salt.
 23. The method of claim 20, wherein adding the effectiveamount of the magnesium compound includes adding the magnesium compoundgenerally along with adding the flocculation aiding metal salt.
 24. Themethod of claim 20, wherein adding the effective amount of the magnesiumcompound includes measuring a quality of the treated water.
 25. Themethod of claim 24, further including adjusting the effective amount ofthe magnesium compound based upon, at least in part, the measuredquality of the treated water.
 26. The method of claim 24, wherein thequality of the treated water includes one or more of an alkalinity ofthe treated water and a pH of the treated water.
 27. The method of claim24, wherein the quality of the treated water includes a corrosivity ofthe treated water as indicated by a Langelier Index of the treatedwater.
 28. The method of claim 20, further including determining ananticipated alkalinity depletion associated with adding the flocculationaiding metal salt, and wherein the effective amount of the magnesiumcompound is based upon, at least in part, amount offsetting at least aportion of the anticipated alkalinity depletion.
 29. The method of claim20, further including adding an effective amount of a polymercontaminant removal aid including one or more ofpolyepichlorohydrin-dimethylamine, polyamine,polydiallyl-dimethylammonium chloride (polyDADMAC), polyacrylate,polyamide, a Mannich polymer, and polyacrylamide.
 30. The method ofclaim 20, wherein removing one or more contaminants from the supplywater includes one or more of flocculation, coagulation, sedimentation,and filtration.
 31. The method of claim 30, wherein removing one or morecontaminants from the supply water includes filtration, and furtherincluding recycling a residual magnesium compound from a filter elementand recycling the residual magnesium compound into the supply water. 32.The method of claim 30, wherein adding the magnesium compound includesadding an admixture of the magnesium compound and an alkaline earthmetal compound.